Modeling the effect of the RB tumor suppressor on disease progression: dependence on oncogene network and cellular context.

The retinoblastoma tumor suppressor, RB, is a key regulator of cellular proliferation that is functionally inactivated at high frequency in human cancer. Although RB has been extensively studied with regard to tumor etiology, loss of tumor-suppressor function often occurs relatively late in tumor progression. Therefore, inactivation of RB could have a profound impact on the behavior of tumors driven by discrete oncogenes. Here, collaboration between Ras or c-Myc deregulation and RB functional state was investigated in a model of conditional genetic deletion to decipher the effects related to disease progression. These studies showed that RB loss had a robust impact on mitogen dependence, anchorage dependence and overall survival, which was significantly modified by oncogene activation. Specifically, RB deficiency predisposed c-Myc-expressing cells to cell death and reduced overall tumorigenic proliferation. In contrast, RB deficiency exacerbated the tumorigenic behavior of Ras-transformed cells in both the model system and human tumor cell lines. As these tumors exhibited highly aggressive behavior, the possibility of exploiting the intrinsic sensitivity to cell death with RB loss was evaluated. Particularly, although Ras-transformed, RB-deficient cells bypassed the G1-checkpoint elicited by pharmacological activation of the p53 pathway, they were also highly sensitized to cell death. Altogether, these data suggest that the impact of RB deletion is dependent on the oncogene milieu, and can directly contribute to transformed phenotypes and response to therapeutic intervention.

Loss of the retinoblastoma tumor suppressor: differential action on transcriptional programs related to cell cycle control and immune function.

Functional inactivation of the retinoblastoma tumor suppressor gene product (RB) is a common event in human cancers. Classically, RB functions to constrain cellular proliferation, and loss of RB is proposed to facilitate the hyperplastic proliferation associated with tumorigenesis. To understand the repertoire of regulatory processes governed by RB, two models of RB loss were utilized to perform microarray analysis. In murine embryonic fibroblasts harboring germline loss of RB, there was a striking deregulation of gene expression, wherein distinct biological pathways were altered. Specifically, genes involved in cell cycle control and classically associated with E2F-dependent gene regulation were upregulated via RB loss. In contrast, a program of gene expression associated with immune function and response to pathogens was significantly downregulated with the loss of RB. To determine the specific influence of RB loss during a defined period and without the possibility of developmental compensation as occurs in embryonic fibroblasts, a second system was employed wherein Rb was acutely knocked out in adult fibroblasts. This model confirmed the distinct regulation of cell cycle and immune modulatory genes through RB loss. Analyses of cis-elements supported the hypothesis that the majority of those genes upregulated with RB loss are regulated via the E2F family of transcription factors. In contrast, those genes whose expression was reduced with the loss of RB harbored different promoter elements. Consistent with these analyses, we found that disruption of E2F-binding function of RB was associated with the upregulation of gene expression. In contrast, cells harboring an RB mutant protein (RB-750F) that retains E2F-binding activity, but is specifically deficient in the association with LXCXE-containing proteins, failed to upregulate these same target genes. However, downregulation of genes involved in immune function was readily observed with disruption of the LXCXE-binding function of RB. Thus, these studies demonstrate that RB plays a significant role in both the positive and negative regulations of transcriptional programs and indicate that loss of RB has distinct biological effects related to both cell cycle control and immune function.

[Examination of a novel wax teat bougie for treatment of wounds in the papillary lactiferous sinus of dairy cows with special regard to endoscopic documentation of mucosal reactions compared with conventional teat bougies and a teat cannula]. / Prüfung eines neuartigen Strichkanalstabes zur Behandlung von Strichkanalwunden unter besonderer Berücksichtigung der endoskopisch dokumentierten Schleimhautverträglichkeit im Vergleich zu konventionellen Zitzenstiften und Verweilkanülen.

The present study on a novel wax-teat bougie, developed by Dr. T. GEISHAUSER for treatment of wounds in the papillary lactiferous sinus of dairy cows, has been performed in two phases of investigation. In a first step, fourteen healthy dairy cows (Deutsch Schwarzbunt) in state of early lactation were dried off temporarily for five days, after checking milk samples of all quarters for six following-on days on their bacteriological status, number of somatic cells, conductivity and results of the California-Mastitis-Test (CMT). The drying off was performed on two Quarters with similar cell-count in milk samples each. In one teat of the selected pairs off udder quarters, the wax-bougie was applied (group I), the other corresponding udder quarters were used as a control (group II). After five days of drying off, lactation was started again after removing the bougies in treated quarters. For another five days milk samples out of the quarters in groups I and II were checked in the laboratory tests named above and mean values and increase differences of results were compared. Comparison of increase differences with t-test showed no statistically significant difference between drying off procedures with the wax-bougie and without any treatment in the parameters named above. Courses of counts of somatic cells, conductivity and CMT showed no significant differences between drying off probands by using the novel wax-bougie and drying off without further treatment. In the second phase of the study, fifteen lactating, healthy dairy cows as probands have been split in five groups. Three cows (twelve udder quarters) were dried off for five days by using the novel teat bougie (group D), in three groups (A,B,C) two different types of conventional teat bougies and one type of cannula were used, and, as a control three cows (group E) were dried off without any treatment. Before drying off the udder quarters and after starting lactation again, the condition of the mucosa in the teat papillary lactiferous sinus has been documented by means of endoscopy and the bacteriological status of milk samples has been determined. As a result all udder quarters dried off temporarily showed endoscopically detectable inflammatory-proliferating reactions in the mucosa of the papillary lactiferous sinus, whereas in cows treated with the novel wax-bougie (group D), as well as in the cows of the control group (E), there were no inflammatory reactions detectable at all. These different reactions, basing on the Fisher-test, have to be considered statistically significant (p < 0.001).

[Endoscopic assessment of the mucosal tolerance of a new papillary duct bougie compared with conventional mammary cannulas]. / Endoskopische Prüfung der Schleimhautver-träglichkeit eines neuartigen Strichkanalstabes im Vergleich zu konventionellen Zitzenstiften und einer Verweilkanüle.

In this study on healthy, milking cows three per group a temporary drying off for five days, using two types of conventional teat bougies (group A, B), one type of a teat canula (group C) and one type of a novel wax-bougie, developed by Dr. Th. Geishauser (group D) was performed. As a control, three cows were dried off without using any teat bougies (group E). Before drying off the udder quarters, the condition of the mucosa in the teat papillary lactiferous sinus was documented by means of endoscopy. After five days, lactation was started and endoscopy was performed again. Endoscopical pictures and video tapes were evaluated for existence of inflammatory-proliferating reactions on the mucosa of the papillary lactiferous sinus. Comparison of the five groups with statistical methods (Fisher test) showed significant (P < 0.001) effects: all udder quarters, dried off temporarily by using conventional teat bougies and teat canulas (groups A, B, C) showed more or less severe alterations in the mucosa of the papillary lactiferous sinus, whereas in cows, treated with the novel wax bougie (group D) as well as in cows of the control group (E) there were no alterations detectable at all.

Self-imaging chirped holographic optical waveguides.

To manipulate light propagation in optical waveguides, we have studied holographic, chirped structures within the waveguide's core. The holographic structures were embedded along the wave propagation direction and extended throughout the entire guide. Various self-imaging guides have been analyzed and realized to demonstrate the effect of different structures.

[Relationship between chemical structure and toxicologic-pharmacokinetic properties of new ampicillin derivatives]. / Beziehungen zwischen chemischer Struktur und toxikologisch-pharmakokinetischen Eigenschaften neuer Ampicillin-Derivate.

The toxicity and the bioavailability of new ampicillin derivatives with glyoxylic acid benzhydrazones as site chain depend on the hydrophobic properties of the site chain. Substituents with lower hydrophobicity (expressed by the hydrophobic substituent constant pi according to Hansch) show a lower toxicity (maximal tolerated doses) and also a lower bioavailability.

[New ampicillin derivatives with glyoxyloylbenzhydrazone side chains]. / Neue Ampicillinderivate mit Glyoxyloylbenzhydrazon-Seitenketten.

New ampicillin derivatives were synthesized from glyoxylic acid benzhydrazones by reaction with chloroformates via mixed anhydrides and ampicillin. These compounds were tested in an agar diffusion test against six different bacterial strains and also for their stability against beta-lactamases. Studies about structure-activity relationships have shown, that the activity against different bacterial strains is influenced in different manner by hydrophilic or hydrophobic and electronic properties of substituents.